[unreadable] The overall goal of this proposal is obtain funding to purchase individually ventilated mouse caging (IVC) systems to meet the rapidly expanding need for genetically altered mouse housing space at Caltech in support of the Biological Sciences Initiative Plan. Emphasis is placed on providing a pathogen-free controlled environment suitable for maintenance of experimental and breeding colonies of genetically altered mice some of which are severely immunocompromised. Based on a survey of current and anticipated mouse housing needs by existing faculty, historical evidence of a 100% increase in the mouse population over a five year period, expansion of total space allocated to the biological sciences by 40%, the addition of several new faculty appointments within the biological sciences within the next 2 years, and continued growth in extramural funding that involves the use of genetically altered mice, it is anticipated that the mouse population at Caltech will continue to grow at a rapid rate. Caltech has responded to this need through construction of a new state-of-the-art animal facility and purchase of initial start-up equipment such as rack and tunnel washers, a bulk autoclave, automatic drinking water system, animal transfer stations, biological safety procedure hoods, and 25 HEPA filtered individually ventilated mouse caging systems (IVC) units. This application requests funding to allow purchase of an additional 23 mouse IVC systems to meet the expanding needs of Caltech investigators for optimal housing for genetically altered mice. Specific aim: To provide 23 HEPA filtered individually ventilated mouse caging systems (IVC) to meet the increasing demand for genetically altered mouse housing by the Caltech research community. [unreadable] [unreadable]